This invention relates to desensitizing teeth and more particularly to a composition, process and apparatus for this purpose.
The principal bulk of human teeth consists of dentin, a calcareous matrix surrounding the pulp and penetrated by numerous tubules. Although the peripheral one-half of the dentin appears to be without nerve endings, the movement of dentinal fluid through these tubules is believed to stimulate pain receptors found closer to the pulp. This is thought to be the mechanism responsible for dentin hypersensitivity, which commonly arises after periodontal surgery or root planing and which produces acute discomfort upon mechanical, thermal, or osmotic stimulation of the tooth (See Braennstroem et al., 1967).
Many of the efforts directed at a reduction of dentin hypersensitivity have sought to impede movement of the dentinal fluid by constricting or occluding the tubule openings. Of particular use have been compounds penetrating the dentinal tubules and causing the formation therein of crystalline precipitates which block fluid movement. Desensitizing compounds which function in this manner are the subject of U.S. Pat. No. 4,057,621 and of other patents cited therein.
A particularly promising desensitizing treatment involves the use of oxalate salts as described in U.S. Pat. Nos. 4,057,621 and 4,538,990 to induce the formation of calcium oxalate and other crystals at the tooth surface. The former '621 patent discloses, at lines 58-68 of column 2, the use of mono- and di-substituted alkali metal and ammonium oxalate solutions in concentrations at or near saturation. These saturated solutions may present problems in general use, however, as variations in shipping and/or storage temperature can bring about precipitation of the oxalate salt and an undesirable cloudiness of the preparation. The latter '990 patent, on the other hand, teaches at lines 57-64 of column 1 a two-step procedure involving the application of a neutral oxalate salt solution followed by an acidic oxalate salt solution. A drawback of such a procedure is the relative inconvenience and costliness of a multiple-step treatment, as well as the increased likelihood of confusing one solution for another. Moreover, the proposed neutral salt of choice (dipotassium oxalate) may be toxic when ingested, posing a risk in the event that over-the-counter distribution or unsupervised use by the patient is desired. Dipotassium oxalate also has been reported to have caused pain upon application.
It is, therefore, an object of the invention to provide a compound for dentin desensitization which is easy to apply without discomfort. A further object is to provide a fast-acting, single-step application which reduces cost, eliminates the potential for confusion between multiple solutions, and allows rapid and convenient desensitization without posing the risk of systemic or tissue toxicity presented by a dipotassium oxalate formulation.
Yet another object of the invention is to provide a desensitizing compound in a form which is stable during shipment and storage, and thus is suitable for commercial distribution to dental professionals and patients. It is also an object to furnish a process and apparatus for the delivery of this compound to dentinal surfaces in a practical, efficient, and economical fashion by both dental professionals and their patients, including a packaging means which enhances the convenience and usefulness of the apparatus.